An air conditioner generally includes an outdoor unit and an indoor unit. The outdoor unit has a heat exchanger, a compressor, a fan, a motor for driving this fan, a printed circuit board and a housing for containing these elements. The indoor unit has a heat exchanger, a fan, a motor for driving this fan, a printed circuit board and a housing for containing these elements. In order to eliminate harm to the environment and collect a valuable material efficiently, a discarded air conditioner is separated into main elements and then smashed and collected according to each element.
As a method for disassembling an air conditioner, the following methods are known, for example.
JP 9(1997)-68325 A discloses a method for cutting and separating a heat exchanger from an indoor unit of an air conditioner by using a cutting machine such as a band saw machine.
Furthermore, JP 9(1997)-68329 A discloses a method for cutting a bottom plate of a housing of an outdoor unit and separating a compressor by using an acetylene gas cutting machine.
Moreover, JP 9(1997)-300127 A discloses a method for cutting and disassembling an outdoor unit by pressing in a shear-type cutting blade.
Other than the above methods, there are some cases where a disc-shaped cutter (a metal slitting saw), a diamond wheel cutter and a grinding tool (a grinder) in which abrasive grains are formed in a disc shape or in a cylindrical shape are used for cutting and separating.
However, the conventional separating methods described above have the following problems.
When using a tool such as a band saw machine or a metal slitting saw, a cutting blade of the tool is pressed strongly against an object to be cut (“an object to be processed”; referred to as “a workpiece” in the following) to cause a continuous shear fracture in the workpiece, thus cutting/processing this workpiece. Since the cutting blade is pressed strongly against the workpiece, frictional heat is generated greatly at the cutting portion. Therefore, the embrittlement and enfeeblement of its cutting edge due to the heat aggravate the abrasion of the cutting edge. Due to the abrasion of the cutting blade, the cutting speed is lowered considerably and thus is limited. In addition, since the cutting blade is allowed to bite into the workpiece, a high stiffness is needed for holding the tool and the workpiece, thus requiring a large-scale holding mechanism and a high equipment cost.
In the gas cutting using a gas such as acetylene, the cutting speed is slow, and if the workpiece itself is combustible or combustibles are present in the vicinity of the cutting section, the cutting is dangerous, so this method has limited utility.
Furthermore, the press-cutting with the shear-type cutting blade needs a great power for holding and moving the blade and holding the workpiece, thus requiring a large-scale apparatus. In addition, the cutting blade easily becomes chipped and worn away.
In the cutting method using a diamond wheel cutter, when the cutting speed is raised, the wear rate of the diamond wheel cutter increases due to frictional heat and therefore the cutting speed is limited. In addition, the diamond wheel cutter is expensive, and the cutting amount and the wear rate of the diamond wheel have a close relationship, resulting in high cutting cost.
The grinder cutting using a grindstone is carried out by causing continuous small shears by cutting surfaces of the abrasive grains. Since the corners (cutting blades) of the abrasive grains are not so sharp and the peripheral speed of the grinder is relatively high, the frictional heat generated at the cutting part is great. In order to secure the lifetime of the grindstone, it is necessary to control the temperature of the cutting part appropriately. Thus, the cutting speed is limited.
In the case where a workpiece including a resin material is cut using a band saw machine, a metal slitting saw, or the like, when the cutting speed is raised, the vicinity of the cutting portion of the workpiece starts burning or melts due to the frictional heat generated by the friction with the tool, thus causing a change in physical properties of the workpiece.
In the case where a workpiece including a metallic magnetic component is cut using a blade made of a material containing a ferroalloy as a main constituent, the fragments and powder that are produced by cutting the workpiece are magnetic substances and thus adhere to the edge of the blade. Consequently, the increase in frictional resistance or the damage to the edge lowers the cutting performance of the blade considerably.
Furthermore, it is extremely difficult to cut a workpiece formed of a plurality of members with different physical properties (for example, metal, resin-molded articles or the like) continuously using the same tool.
When the information required for cutting and processing a workpiece (physical properties or the like) is unknown or when a workpiece is formed of a plurality of members and the shapes and materials of the members hiding behind the surface member are unknown, optimal cutting conditions cannot be found out merely from the image information of the surface and outer shape of the workpiece. Therefore, the automatic control for optimal cutting is impossible.